1) I have a form (form.php) with 2 fields 1-->userName 2--->passwd.2) User fill in the form and submit it.3) The form_check.php file starts a session and proccess the requested form, if the form fields are valid then i set this $_SESSION['userPass']="go";4) When user decides to log-out press log_out link and the log_out.php is executed.5) Here is the log_out.php:

I have checked the session and it has destroyed. But when i press Back button of Internet Explorer it saids me that if i press F5 or Refresh i could see the page i requested.And i am doing that, and the page appears, i also ckecked the session and it has created again.Why is that happening? How could i avoid it?I am confused...